Method and apparatus for selective disabling of tracking of click stream data

ABSTRACT

The invention is a method and apparatus for gathering click stream information from Web surfers while maintaining their privacy. In accordance with the invention, a Web site that collects click stream information provides an opportunity for visitors to choose not to have personal information gathered about them. If a person chooses not to have personal information gathered, the Web site continues to collect click stream information about the visitor&#39;s progress through the Web site as before by the use of cookies and/or URL rewriting, for instance, using Single Pixel technology, in which the client machines are made to send requests to a usage analyzer having cookies bearing the relevant click stream data. However, the cookies include an extra field called a privacy flag. If the visitor chooses not to have personal information gathered, the flag is set. Otherwise it is reset. The usage analyzer software checks the privacy flag in the cookie of each request it receives and, if the flag is set, replaces the data in any field of the corresponding log entry containing personal information with a default value. Accordingly, the Web site operator can continue to gather click stream information from visitors without collecting personal information.

FIELD OF THE INVENTION

[0001] The invention pertains to the collection by Web site operators ofinformation about Web site usage by individuals. More particularly, theinvention pertains to the collection of information relating to users'identities in such environments.

BACKGROUND OF THE INVENTION

[0002] The Internet is a vast collection of computing resources,interconnected as a network, from sites around the world. It is usedevery day by millions of individuals. The World Wide Web (referred toherein as the “Web”) is that portion of the Internet that uses the Hypertext Transfer Protocol (“HTTP”) as a protocol for exchanging messages.(Alternatively, the “HTTPS” protocol can be used, where this protocol isa security-enhanced version of HTTP.)

[0003] A user of the Internet typically accesses and uses the Internetby establishing a network connection through the services of an InternetService Provider (ISP). An ISP provides computer users the ability todial a telephone number using their computer modem (or other connectionfacility, such as satellite transmission), thereby establishing aconnection to a remote computer owned or managed by the ISP. This remotecomputer then makes services available to the user's computer. Typicalservices include: a search facility to search throughout theinterconnected computers of the Internet for files of interest to theuser; a browse capability for displaying information files located withthe search facility; and an electronic mail facility, with which theuser can send and receive mail messages from other computer users.

[0004] The HTTP communications protocol uses a request/responseparadigm, where the electronic messages sent between communicatingcomputers can be categorized as either requests for information orresponses to those requests.

[0005] The user working in a Web environment will have software runningon his or her computer to allow him or her to create and send requestsfor information onto the Internet, and to see the results. Thesefunctions are typically combined in a software package that is referredto as a “Web browser”, or “browser”. After the user has created arequest using the browser, the request message is sent out into theInternet (typically, via an ISP as described above). The target of therequest message is one of the interconnected computers in the Internetnetwork. That computer receives the message, attempts to find the datasatisfying the user's request, formats that data for display with theuser's browser, and returns the formatted response to the browsersoftware running on the user's computer.

[0006] This is an example of a client-server model of computing, wherethe computer at which the user requests information is referred to asthe client or client machine, and the computer that locates theinformation and returns it to the client is the server or servermachine. In the Web environment, the server is referred to as a “Webserver”.

[0007] Content on the Internet is served in individual files in the formof HTML pages. HTML (Hyper Text Markup Language) is a Web contentformatting language specifically designed for a distributed network suchas the Internet. An HTML page contains HTML code, which indicates howthe information content is to be displayed, as well as at least some ofthe actual content. Pages also typically contain references to otherfiles where at least some of the content is contained. Web browsersoftware is designed to issue requests for pages in the form of URLs(Universal Resource Locators). A URL essentially is an address of a filethat is accessible through the Internet. The URL includes the name ofthe file that is being requested and the IP (Internet Protocol) addressof the server on which it is to be found.

[0008] A user at a client machine may type a URL into an appropriatefield in a GUI (Graphical User Interface) generated by the Web browsersoftware in order to address Web pages. Another way of addressing Webpages is by hyperlinking. A hyperlink is a portion in one Web page, suchas a portion of text or an image, that, when selected (such as bypositioning a cursor over that portion and pressing a button on thecursor control device), automatically addresses another Web page. Thus,for example, by manipulating one's mouse to cause the screen cursor tomove over a hyperlink and clicking, the page addressed by that hyperlinkis accessed by the browser.

[0009] Each request is routed through the Internet to the serveridentified in the URL. That server then returns the requested pagethrough the Internet to the client machine that requested it. The Webbrowser software reads the HTML code in the page and, if that pagecontains references to other files containing some of the content, thebrowser software sends further requests for those files. It displays thecontent (whether contained directly in the HTML page or in another filereferenced within the HTML page) in a manner dictated by the HTML codein the page.

[0010] Countless commercial, educational, government and otherinstitutions operate servers containing HTML pages that are accessibleto client machines via the Internet. The term “Web site” generallyrefers to a collection of HTML pages that are maintained on (orgenerated on-the-fly by) one or more servers by or on behalf of a singleentity and that are related to each other in some fashion.

[0011] HTTP does not provide for maintaining any type of stateinformation about the communications, instead treating eachrequest/response pair as a separate and unrelated transaction. However,there are many cases for which it is desirable to associate multipleHTTP requests from a client to a server with each other so as to be ableto maintain state information.

[0012] One example scenario where state information is an absolutenecessity is on-line shopping, including the gathering of user profileinformation. In on-line shopping, a user typically accesses a seller'son-line catalog, which will be displayed to the user as some number ofWeb pages. Typically, the user can display a separate page ofinformation related to each product, to read about the details of thatproduct. Typically, each time the user requests to see a page, aseparate HTTP request is sent to the Web server where the seller'sproduct catalog is stored. When the user wishes to order a product, heindicates his selection by clicking on an “Order” button of some typeusing a mouse, for example. This causes another request message to besent to the server, where the request indicates that this is an orderfor the particular item.

[0013] Without the ability to maintain state information, each of theserequests would be treated as unrelated to the others. There would be noefficient way to collect orders for more than one item into one largeorder. Further, there would be no efficient way to allow the user toenter his name, address, credit card number, etc. only one time, andhave that information apply to all the ordered items.

[0014] Even further, it also frequently is desirable to be able tomaintain state information across multiple, separate, visits by aparticular individual to a particular Web site. For instance, it may bedesirable for a retail Web site to store all of the information that ittypically gathers to process a purchase order by an individual andassociate that information with the individual every time he or shevisits the Web site. Then the individual will not need to re-enter thesame information, such as name, credit card No., billing address,shipping address, etc., every time he or she visits the Web site andpurchases an item.

[0015] Accordingly, ways have been developed outside of the HTTPprotocol itself for maintaining such state information. One of theearliest ways developed for doing this was the use of cookies.

[0016] Cookies are small data files that a server might send to a clientmachine and that the client's Web browser knows to store in a designatedcookie folder. A cookie contains pertinent information about the user aswell as information that the browser uses to determine the particularWeb site (i.e., URL) to which the cookie pertains. Thereafter, when thatclient machine sends a HTTP request for a Web page meeting the URLcriteria set forth in the cookie, the client's Web browser softwareincludes that cookie in the request. The purpose of cookies is to informa server of relevant information about the particular user (or at leastthe particular client machine that issued the request). Cookies mightcontain any particular information that a Web site operator feels theneed to have in order to better service its customers.

[0017] URL rewriting is a technology that can serve most of the samefunctions as cookies for situations in which cookies are disabled on aparticular client machine or if cookies are otherwise undesirable orimpossible to use. Briefly, in URL rewriting, the data that would havebeen contained in a cookie is appended to the end of the URL in therequest. URL rewriting and particularly its use as a substitute forcookies is well known in the art.

[0018] Large Web site operators may own their own server (or a serverfarm comprising multiple servers) dedicated to a single “Web site”. Onthe other hand, smaller Web site operators may farm out maintenance oftheir Web sites to other companies that might support multiple Web siteson a single physical server machine. These companies are commonly calledWeb hosts or Web hosting companies.

[0019] Many Web site operators, and particularly commercial Web siteoperators, have a desire to identify and attract as many persons aspossible with an interest in the particular subject matter of the Website as often as possible. One step that typically is necessary toachieve this goal is to collect personal information about theindividuals that visit the Web site. Such information provides at leasttwo avenues of attracting visits. First, personal information such as email address, mailing address and telephone number enable the Web siteoperator to contact the individual with advertising or other informationof interest. Secondly, a collection of demographic information about alarge number of visitors to the Web site may enable a Web site operatorto determine demographics of its target audience and thus better targetadvertising or other information to persons with similar demographicprofiles.

[0020] Personal information can be collected by asking visitors to theWeb site to provide personal information in an online form orquestionnaire.

[0021] The same type of personal and demographic information aboutindividuals that visit other Web sites that have similar focuses as (orfocuses that are known to have a high demographic cross-correlationwith) the focus of the particular Web site also can be useful intargeting advertising towards those individuals.

[0022] Many companies are willing to sell or otherwise share thepersonal information it gathers about visitors to its Web site withother companies.

[0023] Another aspect of attracting and keeping customers is making Websites as convenient and attractive to users as possible so that theywill be more inclined to return to the Web site. Accordingly, many Website operators have a strong desire to keep track of the ways in whichindividuals utilize the Web site in order to determine which aspects ofa Web site users like or dislike. Useful information in terms of makingsuch determinations include things such as (1) from what other Web sitesusers have hyperlinked to your Web site, (2) which pages on your Website receive the most and/or fewest hits, (3) how long users tend toview a particular page, (4) on which pages users have entered the Website, (5) from which pages users have exited the Web site (to go toanother Web site or log off the Internet altogether), and (6) theparticular browser software used by visitors. This type of data iscommonly termed click stream data.

[0024] Traditional log file analysis techniques can be used to gatherclick stream data of users of a particular Web site to develop a log ofdata indicating the page (or resource) requests made by Web site usersin order to collect some of the aforementioned useful information.

[0025] As is well known to those of skill in the art of Web site designand Web hosting, cookies are used extensively in gathering and trackingsuch information. For instance, a cookie identifying the particular user(or at least the particular client machine) can be included in eachrequest, thus allowing tracking of one's progress through a Web site.The same objectives can be accomplished using URL rewriting.

[0026] A technology called “Single-Pixel” technology has been developedthat can be used to gather information similar to the informationgathered through traditional log file analysis. With Single-Pixeltechnology, tags can be embedded in an HTML page that cause the browserat the client machines that receive that page to send click streaminformation in the form of cookies (or rewritten URLs) to a click streamanalysis (also called a usage analyzer) engine on a server on the Web.That server typically is (but need not be) a separate server from theserver of the particular Web site that is serving the content responsiveto the client machine's requests. Other methods also are known forsending Single-Pixel data for collecting click stream information. Suchother methods include query string parameters and hidden form data. Theusage analyzer engine maintains a log containing information for eachrequest it receives. The log entries can be analyzed and correlated toderive the aforementioned type of information.

[0027] Web hosting companies are particularly interested in click streamand other Web site usage information and often share such informationgathered with respect to each of the companies to which it provides Webhosting services (i.e., its customers) with all of its customers.

[0028] Many individuals who use the Internet find this sort of gatheringof personal information and Web surfing habits about themselvesoffensive or do not want such information about them to be gathered.

[0029] Accordingly, it is an object of the present invention to providean improved method and apparatus of gathering click stream information.

[0030] It is another object of the present invention to provide a methodand apparatus for gathering click stream information while preservingthe privacy of the individuals from whom the information is gathered.

SUMMARY OF THE INVENTION

[0031] The invention is a method and apparatus for gathering clickstream information from Web surfers while still maintaining theirprivacy. In accordance with the invention, a visitor to a Web site thatcollects click stream information provides an opportunity to visitors tochoose not to have personal information gathered about them. If a personchooses not to have personal information gathered, the Web site cancontinue to collect click stream information about the visitor'sprogress through the Web site by the use of cookies and/or URLrewriting, including the use of Single Pixel technology as before,except that the cookie, query parameters, or form data includes an extrafield called a privacy flag. If the visitor chooses not to have personalinformation gathered, the flag is set. Otherwise it is reset.Alternately, the mere presence of a privacy flag can be used to indicatea request for privacy. The usage analyzer engine checks the privacy flagin the data of each request it receives and, if the flag is set, itreplaces the data in any field of the corresponding entry in the clickstream log that contains personal information with a default value.Accordingly, the Web site operator can continue to use cookies andSingle Pixel technology to gather click stream information fromvisitors, including demographic information, without collecting personalinformation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a block diagram illustrating the basic componentsinvolved in the practice of the present invention in connection with adistributed network.

[0033]FIG. 2 is a flow diagram illustrating steps performed inaccordance with one aspect of the present invention.

[0034]FIG. 3 is a flow diagram illustrating steps performed inaccordance with another aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035]FIG. 1 is a block diagram of a network, such as the Internet, inwhich the present invention can be implemented. The network is shown asblob 14 and comprises a series of interconnected computers, routers andswitches (not shown) that essentially allow any computer on the networkto communicate with any other computer on the network. Computers 12 athrough 12 e are client computers that issue requests via the Internetto server machines on the Internet. Computers 16 a through 16 d areservers that serve information to client machines responsive to requestsreceived from those client machines via the Internet. Those of skill inthe art will understand that some Web site operators maintain aplurality of servers (sometimes called a server farm) for a single Website. On the other hand, other companies, such as Web hosting companies,maintain multiple Web sites for multiple customers on a single server.However, in order not to obfuscate the invention, we shall assume thateach server 16 a-16 d is operated by a single Web site operator in thisdiscussion.

[0036] Let us assume that server 16 a supports a large commercial Website that offers for sale all forms of electronic equipment, includingcomputers, audio products, televisions and other video products,software, printers, and accessories for all of the above. Let us alsoassume that the Web site operator wishes to collect click streaminformation as well as personal information from its visitors. The Website utilizes cookies and/or URL rewriting and Single-Pixel technologyin a manner well known in the prior art to collect click streaminformation from its visitors. Personal information also is gathered inthe usual manner, including the use of electronic forms in which theuser is requested to provide such information. Even if the Web site doesnot have such a form for all visitors, any visitor who has purchasedanything through the Web site had to have provided such information atthe time of purchase in order to complete the purchase. The Web siteoperator can associate the personal information with the click streamdata either by embedding the personal information directly within thecookies sent to the client machines' cookie folder or by placing aunique ID in those cookies, which ID can be later associated with theuser's personal information maintained locally by the Web site operator.In either event, the click stream data is sent to a usage analyzersoftware engine on a separate server 16 b. As previously mentioned, withSingle-Pixel technology, tags are embedded in the HTML pages of the Website that cause the browsers at the client machines that receive thepages to send click stream information in the form of cookies, URLparameters, hidden form data, etc. to the usage analyzer server 16 b.

[0037] Thus, the log generated by the usage analyzer will eitherdirectly contain personal information or contain user IDs from which itwill be possible to retrieve the personal information.

[0038] However, in accordance with the present invention, the user IDand/or personal information contained in the log can be eliminated,either automatically for all log entries or only for those log entriesfor which the corresponding user has indicated a desire to blockpersonal information.

[0039] It generally will not be practical to eliminate personalinformation from cookies, especially the cookies used in connection withthe gathering of click stream information through the usage analyzerengine. Specifically, it is generally necessary to maintain some stateinformation so that individual requests from a single client machine canbe associated with each other at the Web site. As previously described,this usually is necessary to provide a satisfying web surfing experiencefor visitors and is an absolute necessity for essentially any type oftransaction, such as sales transactions. Thus, in accordance with theinvention, in the log created and maintained by the usage analyzerengine, any fields of information in a received cookie deemed tocomprise personal information are overwritten with a default value thatcontains no personal information about the visitor (or client machine)from which it was received. The overwriting can be applied to any fieldor type of information in the entry. Accordingly, the term “personalinformation” as used herein essentially can be whatever information theWeb site operator or user deems it to be. In fact, the invention can beapplied to any type of information and is not necessarily restricted toblocking “personal information”.

[0040] In a simple embodiment of the invention in which a Web siteoperator simply does not wish to maintain personal information in theusage analyzer about any of its users, the overwriting described abovecan be applied to every log entry. In such an embodiment, there would beno need for a privacy flag or the like. However, in a more practicalembodiment of the invention, each visitor to the Web site is given anopportunity to read the Web site's privacy policy statement. In thatpolicy statement, the user is given at least two options, namely, toallow the Web site to apply its basic privacy policy in connection withinformation gathered from that user or to select an enhanced privacylevel in which certain types of information about the user are notcollected. If the user selects the enhanced privacy level, then a schemein accordance with the present invention is utilized to rewrite fieldsin the log with default data containing no identity information. One wayof implementing this aspect of the invention is to include in thecookies that the Web site sends to the browsers of its visitors anadditional, “privacy flag” field. The privacy flag can be a one bitfield which, when in a first condition (e.g., logic 0) denotes that thevisitor has not requested enhanced privacy and when in a secondcondition (e.g., logic 1) denotes that the visitor has requestedenhanced privacy. In an alternate embodiment, a request for enhancedprivacy might be indicated by the presence of the privacy flag, whereasthe absence of the privacy flag indicates that the users has notrequested enhanced privacy.

[0041] It should be understood that the Web site operator may offer morethan two levels of privacy. Each increasing privacy level translatinginto additional fields of data that will be overwritten with defaultvalues. In such cases, the flag would need to be more than one bit widein order to denote which of the multiple privacy levels for which avisitor has opted.

[0042] In any event, when the usage analyzer engine receives cookies, itparses them to retrieve the click stream and/or other information thatwill be placed in the corresponding log entry. As part of the parsing,it encounters the privacy flag, determines its condition and, dependingon its condition, overwrites one or more fields in the log entry withdefault data that does not contain any personal information.

[0043] In this manner, those users requesting a certain level ofprivacy, can have that privacy while still allowing the Web siteoperator to collect as much other information as it desires. Forinstance, if we consider a simple example in which the only “personalinformation” in the cookie is a user ID, that field can be replaced witha default field yet the logged entry will still contain the useful clickstream information (as well as all other information that may have beenin the cookie). Thus, the Web site operator still can gather clickstream and/or demographic information from all visitors withoutgathering actual personal information. Thus, the Web site operator willstill be able to obtain useful information such as the other Web sitesfrom which visitors tend to arrive at the present Web site, the pages ofthe Web site where users tend to enter and exit, the manner in whichuser's tend to progress through the Web site, the pages of the Web sitethat receive the most hits, the pages of the Web site that receive thefewest hits, etc.

[0044]FIGS. 2 and 3 are flow diagrams illustrating a process inaccordance with the present invention. It should be apparent from thepreceding discussion that implementation of the invention involves stepscarried out at potentially three different computers coupled by thenetwork, namely, the Web site server, the client machine, and the usageanalyzer server. The Web site server and the usage analyzer server, ofcourse, may or may not be the same physical computing device. Further,it will be understood that, while the client machines participate in theexecution of the overall process, the client machines require nomodification whatsoever to participate in the process of the presentinvention. In essence, the only difference at the client machine is thecontents of the messages (e.g., cookies or URLs) that it receives fromthe servers. More particularly, the cookies may contain an extra field,namely, the privacy flag field.

[0045]FIG. 2 illustrates steps performed at the Web site server, whichare the steps relating to the determination and setting of a privacylevel. The process is entered at step 201. The Web site operator has anynumber of options for how and when this routine is entered. Forinstance, it may be entered whenever a visitor first visits a Web site(as, for instance, determined by the lack of a cookie pertaining to thisWeb site contained in the request). Alternately, the user would have tonavigate to the privacy policy of his own volition. Whatever the mannerin which it is reached, the Web site presents its privacy policy to theuser in step 201 wherein the user is given the option to designate adesired privacy level. In this example, let us assume that there areonly two options. In step 203, it is determined whether the user hasrequested enhanced privacy or not. If the user requests enhancedprivacy, flow proceeds to step 205 where a cookie containing whateverinformation the Web site deems desirable is created. The cookie includesa privacy flag with that privacy flag being set to indicate enhancedprivacy. If the user does not request enhanced privacy, flow insteadproceeds from step 203 to step 207, where the same cookie is createdexcept that the privacy flag is set to no enhanced privacy. Then, fromeither step 205 or step 207, flow proceeds to step 209 where the cookieis sent to the user. The process ends at step 211.

[0046]FIG. 3 is a flow diagram illustrating the processing within theusage analyzer engine pertaining to the present invention. In step 301,the usage analyzer engine receives a request from a client machinecomprising click stream and/or other data in accordance withSingle-Pixel technology. In step 303, the usage analyzer engine parsesthe request and the cookie contained in the request. In step 305, itdetermines whether the privacy field of the cookie is set to enhancedprivacy. If the cookie is set to enhanced privacy, flow proceeds to step307 where the personal information fields(s) of the cookie areoverwritten with default data. Flow then proceeds to step 309, where anentry is created in the log corresponding to that request.

[0047] If the privacy field in the cookie is not set to enhancedprivacy, flow simply proceeds from step 305 directly to step 309, wherethe entry is created in the log with the original data in the personalinformation fields. The process ends at step 311.

[0048] As is well known, all requests issued by client machines includeas part of the request an IP address of the requesting client machine.In the case of client machines that access the Internet through an ISP,the client machine is assigned a new IP address each time it logs on tothe Internet through the ISP. Client machines that have a more directconnection to the Internet typically have a single IP address that doesnot change. In either event, the IP address of the client machine can beconsidered personal information. For instance, even in the case ofclient machines that access the Internet through an ISP, the ISP maymaintain records through which the IP address can be correlated to aparticular individual or client machine. Accordingly, the presentinvention can also be applied to the IP address contained in therequest. More particularly, if the Web site operator includes an IPaddress field in its log at the Usage Analyzer server, that informationcan be overwritten with default data if the user selects enhancedprivacy. Alternately, in those embodiments of the invention in which theWeb site operator universally does not collect certain types of privateinformation, the IP address field can be overwritten with default datain all of the log entries.

[0049] While the invention has heretofore been described in connectionwith the Internet and the Web, it is applicable to any networkenvironment in which client machines coupled to said network requestnetwork resources (files) from servers coupled to said network.

[0050] Having thus described a few particular embodiments of theinvention, various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications and improvements as are made obvious by this disclosureare intended to be part of this description though not expressly statedherein, and are intended to be within the spirit and scope of theinvention. Accordingly, the foregoing description is by way of exampleonly, and not limiting. The invention is limited only as defined in thefollowing claims and equivalents thereto.

We claim:
 1. A method of collecting click stream data about usage of Websites by users who visit said Web site via the Internet using clientmachines while enhancing privacy of said user, said method comprisingthe steps of: providing said user an opportunity to designate a desirethat certain data about said user not be collected; if a user makes saiddesignation instructing said client machine corresponding to said userto include said designation in requests pertaining to said Web site; andresponsive to receipt of requests from said client machine containingsaid designation, replacing said certain data with other data. 2 Themethod of claim 1 wherein said instructing step comprises sending acookie to said client machine including a data item disclosing saiddesignation. 3 The method of claim 1 wherein said instructing step isperformed using URL rewriting. 4 The method of claim 1 furthercomprising the step of: including said instruction in pages sent to saidclient machine instructing that client machine to include saiddesignation in said requests. 5 The method of claim 4 wherein said pagesutilize Single-Pixel technology to track click stream data. 6 The methodof claim 4 wherein said instructions in said pages comprise Single-Pixeltags. 7 The method of claim 4 wherein said certain data comprisesinformation from which the identity of said user can be determined.
 8. Amethod of collecting click stream data about usage of Web sites by usersof said Web site who visit said Web site using client machines whileenhancing privacy of said users, said method comprising the steps of:providing said users an opportunity to choose between at least first andsecond privacy levels, said first privacy level indicating that at leasta first data item about said user not be collected and said secondprivacy level indicating that said data item may be collected; sendingcookies to said users' client machines, each said cookie including aplurality of data items, including, at least, said first data item and asecond data item, said second data item comprising said privacy leveldesignation, said cookie to be included in requests issued by saidclient machine that meet certain criteria; including in HTML pages sentto said client machines instructions for that client machine to send arequest to a designated server, said request including said cookie;receiving said requests at said designated server; parsing said requeststo determine which of said first and second privacy levels isdesignated; with respect to requests designating said first privacylevel, storing data items from said cookie in a memory and replacingsaid first data item of said cookie with other data; and with respect torequests designating said second privacy level, storing data items fromsaid cookie in a memory without replacing said first data item of saidcookie.
 9. The method of claim 8 wherein said Web pages utilizeSingle-Pixel technology to track click stream data.
 10. The method ofclaim 8 wherein said designated server generates log files to track saidclick stream data.
 11. The method of claim 9 wherein said instructionsin said Web pages comprise Single-Pixel tags.
 12. The method of claim 8wherein said second data item comprises information from which theidentity of said user can be determined.
 13. The method of claim 8wherein said second data item comprises a user ID.
 14. The method ofclaim 8 wherein said second data item comprises an IP address.
 15. Acomputer program product embodied on a computer readable medium forcollecting click stream data from client machines coupled to a network,said client machines sending requests to a server coupled to saidnetwork, said requests containing user identification data and saidclick stream data, said computer program product comprising: firstinstructions for receiving and parsing said requests to identify saiduser identification data and said click stream data; second instructionsfor replacing said user identification data with other data; thirdinstructions for creating a data entry containing said click stream datacontained in said request associated with said other data and not withsaid user identification data.
 16. The computer program product of claim15 wherein said user identification data comprises a data field in acookie contained in said request.
 17. The computer program product ofclaim 15 wherein said user identification data is contained in arewritten URL in said request.
 18. The computer program product of claim15 wherein said user identification data is contained in URL parameterdata.
 19. The computer program product of claim 15 wherein said useridentification data is contained in hidden form data.
 20. The computerprogram product of claim 15 wherein said requests further comprise aprivacy level designation, said privacy level designation indicating atleast whether or not said user identification data should be maintainedby said computer program product, said computer program product furthercomprising: fourth instructions for identifying said privacy leveldesignation; and fifth instructions for bypassing said thirdinstructions if said privacy level designation indicates that saidcomputer program product should maintain said user identification data.21. A method of collecting data about usage of network server resourcesby client machines while enhancing privacy of users of said clientmachines, said method comprising the steps of: providing said users anopportunity to designate that said user desires that certain data aboutsaid user not be collected; if a user makes said designation,instructing said client machine corresponding to said user to includesaid designation in requests for network server resources; andresponsive to receipt of requests from said client machine containingsaid designation, replacing said certain data with other data.